It's interesting to watch the evolution of global warming as a political issue in the United States. At the Aspen Ideas Festival, for example, former president Bill Clinton pushed the climate to the top of his agenda, arguing that action on global warming would have a variety of benefits: "We've got to make it a national security argument and we've got to make it a jobs argument and we've got to make the price of oil irrelevant," Clinton said, suggesting the country could create millions of jobs if alternative energy efforts received a fraction of the tax incentives that go to "old energy."

What's notable here is that Clinton represents a very visible face for the Democratic Party, and if he is in fact pushing this as his key focus, we can expect to see the subject become a more frequent element in American political discourse.

Hillary Clinton and Wesley Clark, each of whom had their own moment in the spotlight at the Ideas Festival, were equally eloquent and emphatic on climate change. And so was Jim Woolsey, former Director of Central Intelligence, who impressed many with his aggressive stance on renewables and his deep understanding of the national security threats emanating from climate change.